Electric cord or cable



Patented May 25, 1937 UNITED STATES PATENT OFFICE ELECTRIC CORD R CABLE New Jersey,

a corporation of New Jersey Application September 27, 1934, Serial No. 745,821

1 Claim.

This invention relates to electric cords or cables of the type having multiple conductors arranged in parallel relationship and .individually insulated with rubber compound, one of the objects being to use the rubber compound insulation of at least one of the conductors of such a cord or cable so as to permanently provide the latters characteristically smooth fiat surface, whereby the fillers customarily used for this purpose may be eliminated.

Attention is called to the fact that the present case is a continuation in part of an application entitled Cables, filed by the present inventor on November 14, 1932, and bearing Serial No. 642,641.

Referring to the accompanying drawing:

Figure 1 is a cross-section of a disassembled cord or cable embodying the features of the invention.

Figure 2 is a cross-section of the completed cord or cable.

Figure 3 is an elevation of the cord or cable.

Figure 4 is a cross-section of a disassembled cord or cable embodying the principles of the 25 invention in a modified form.

Figure 5 is a cross-section of this modified cable in completed form.

Figure 6 is an elevation of this modified cable.

The electric cord or cable shown by Figures 1,

30 2, and 3 has two substantially cylindrical conductors l of the same diameters arranged in parallel relationship and insulated with individual coverings 2 and 3 of rubber compound of the necessary thicknesses, it being understood that high grade rubber stock is ordinarily used for this purpose and that such stock is rather elastic. The covering 2 has an outside 4 that is cylindrical. The other covering 3 has an outside that includes a longitudinally extending semicylindrical groove 5 of the same radius as that of the outside 4 of the covering 2. It also has fiat surfaces 6 which proximately bound the groove 5 and extend tangentially away therefrom. It follows that the surfaces 6 are respectively parallel and that the distance separating them is the same as the diameter of the outside 4 of the covering 2. The surfaces merge into a semi-cylindrical surface 1 which is positioned diametrically opposite the groove 5 and. which functions to complete the protection of the strand to which the covering 3 is applied.

The covering 2 is snugly fitted into the groove in the covering 3 and means are provided for holding the two together with the outside 4 of the covering 2 in complete contact with the groove 5 included by the outside of the covering 3. Such means may constitute a belt 8, illustrated by Figures 2 and 3. In case the use of such a belt is undesirable, the two coverings may be vulcanized together.

It is to be particularly noted that the parts of the covering 3 that lie between the mutually adjacent portions of the groove 5 and surfaces 6 are of relatively small cross-sectional areas. Therefore, these parts are flexible and can be easily permanently held in their proper position by the belt 8, or by a vulcanized bond between the outside 4 of the covering 2 and the groove 5. This is important because the rubber compound is relatively elastic and becomes resilient when the cable is bent or twisted.

If these parts were of larger cross-sectional areas the resiliency resulting from such bending would be sufiiciently great to cause a projection or longitudinally extending ridge to form in the belt 8. Also, if vulcanization is depended upon, the resiliency will be sufficiently great to put a severe strain on the vulcanized bond so that the latter might eventually loosen.

The modified cable shown by Figures 4 through 6 is substantially the same as the cable shown by the first three figures, excepting that the sur-- faces 6 do not merge into the semi-cylindrical surface I but instead bound a second groove 5, and a second conductor l provided with a rubber compound covering 2 having a cylindrical surface 4 is provided, this covering 2* being fitted into the groove 5 in the same manner already described. Here again a belt 8 may be used to hold the various parts together. canized bond may be used.

This modified cable has the same advantages respecting the ability of its covering 3 to permanently provide a smooth and fiat exterior as is possessed by the cable first described. In all cases the portions of the rubber compound which must hug the cylindrical outside of the other covering are of such shapes that they are surficiently flexible and of sufficiently small crosssectional areas to stay in place when the cable is bent or twisted, in spite of the resulting resilient forces.

I claim:

An electric cord or cable having at least two substantially cylindrical conductors of the same diameters arranged in parallel relationship and insulated with individual coverings of elastic material of the necessary thicknesses, one of said coverings having an outside that is cylindrical Also, a vuland the other of said coverings having an outside that includes a longitudinally extending semi-cylindrical groove of the same radius as that of the outside of the first named covering, and flat parallel surfaces which proximately bound said groove and extend tangentially away therefrom, the first named covering being snugly fitted into the groove in the second named covering and means provided for holding the two together with. the outside or the first named covering in contact; with said groove included by the outside of the second named covering.

OWEN A. MCNAMEE. 

